Critical Organs

in radiobiology, the structures, tissues, and organs that cannot be irradiated without leading to a substantial disruption of the vital processes.

The critical organs include the hemopoietic organs, including the bone marrow; the epithelium of the gastrointestinal tract, whose affection may lead to the death of the organism; the crystalline lens of the eye; and the gonads (irradiation of the gonads may cause infertility or produce genetic defects).